Invertebrate cytokines II: Release of interleukin-1-like molecules from tunicate hemocytes stimulated with zymosan

Conditioned media and cell extracts from tunicate hemocytes that had been cultured with a variety of antigenic stimulants were tested for interleukin-1 (IL-1)-like activity. Media conditioned by hemocytes stimulated with zymosan significantly increased the proliferative and phagocytic activities of tunicate hemocytes. SDS-PAGE indicated that these biological activities were associated with the adaptive release of tunicate IL1-like (tunicate IL-1) molecules by stimulated hemocytes. The data suggest that tunicate IL1 molecules are expressed in response to selected antigenic stimuli. Such responses may form the basis for nonclonal, inducible immune reactions among phylogenetically primitive animals.